A Complex Competitive Exclusion Culture Reduces Colonization in Broiler Chickens at Slaughter Age In Vivo.

Diminishing prevalence in poultry flocks has proven to be extremely challenging. To date, efficacious control measures to reduce prevalence are still missing. A potential approach to control in modern poultry productions is to occupy its niche in the mucosal layer by administering live intestinal microbiota from adult chickens to dayold-chicks (competitive exclusion (CE)). Therefore, this in vivo study investigates the efficacy of a complex CE culture to reduce () colonization in broiler chickens. For this purpose, the complex CE culture was applied twice: once by spray application to day-old chicks immediately after hatching (on the 1st day of life) and subsequently by an additional application via drinking water on the 25th day of life. We observed a consistent and statistically significant reduction of counts in cloacal swabs throughout the entire fattening period. At the end of the trial after necropsy (at 33 days of age), cecal counts also showed a statistically significant decrease of 1 log MPN/g compared to the control group. Likewise, colon counts were reduced by 2.0 log MPN/g. These results suggest that CE cultures can be considered a practically relevant control strategy to reduce colonization in broiler chickens on poultry farms.